DESCRIPTION: Component 1 (Overview): The MTN Leadership Group comprises a Leadership Operations Center (LOC), Laboratory Center (LC), and Statistical and Data Management Center (SDMC), for each of which thematically linked but separate applications have been submitted. The LOC is led by two Principal Investigators: Drs. Sharon Hillier and Ian McGowan, both located at the Magee Womens Research Institute in Pittsburgh, each providing distinct but complementary expertise. Dr. Hillier provides primary leadership for MTN's vaginal microbicide development and female reproductive health; Dr. McGowan leads the MTN rectal microbicide research agenda and mucosal immunology program. The LOC also comprises the PIs for the Operations Support Core (Cates), University of Washington Core (Celum), the LC (Dezzutti), and the SDMC (Brown), which work together and with the network-affiliated Clinical Trial Units/Sites to implement the research agenda. The LOC is supported by 3 Working Groups--Biomedical Science, Behavioral Research, and Community--and 3 Network Committees: Study Monitoring, Network Evaluation, and Manuscript Development. The PIs and the Chairs of the Working Groups and Network Committees constitute the MTN Executive Committee, the primary decision-making body for MTN activity. Established in 2006 with NIH funding, the MTN was charged with developing safe and effective microbicides from the early stages of product development through final approval by regulatory authorities. The present grant application details MTN contributions to HIV prevention, defines network leadership and operational structures for the next funding cycle--a 7-year period from 12/1/13 through 11/30/20-and describes 6 specific areas of challenge and needed improvement. The application presents 15 Specific Aims for MTN that build on its 6 years of experience with developing and/or completing 33 clinical protocols, associated lessons learned, obstacles encountered, gaps identified; and environmental changes and pressures.